[Backport] Revert "unbundle agent and remove associated code (#31228)" (

#31796) (#32160)

Co-authored-by: Alex Lopez <[email protected]>

cmd/agent/launcher/launcher.c

@@ -0,0 +1,32 @@
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#ifndef DD_AGENT_PATH
+#error DD_AGENT_PATH must be defined
+#endif
+
+#ifndef DD_AGENT
+#define DD_AGENT "agent"
+#endif
+
+int main(int argc, char **argv) {
+    if (argc > 1) {
+        argv[0] = DD_AGENT;
+    } else {
+        argv = malloc(sizeof(char *) * 2);
+        argv[0] = DD_AGENT;
+        argv[1] = NULL;
+    }
+
+    if (strlen(DD_AGENT_PATH) == 0) {
+        fprintf(stderr, "Cannot determine agent location\n");
+        exit(1);
+    }
+
+    setenv("DD_BUNDLED_AGENT", DD_AGENT, 0);
+
+    execvp(DD_AGENT_PATH, argv);
+    return 1;
+}

cmd/agent/main.go

@@ -9,13 +9,62 @@
 package main
 
 import (
+	"fmt"
 	"os"
+	"path"
+	"strings"
 
 	"github.com/DataDog/datadog-agent/cmd/agent/command"
 	"github.com/DataDog/datadog-agent/cmd/agent/subcommands"
 	"github.com/DataDog/datadog-agent/cmd/internal/runcmd"
+	"github.com/spf13/cobra"
 )
 
+var agents = map[string]func() *cobra.Command{}
+
+func registerAgent(names []string, getCommand func() *cobra.Command) {
+	for _, name := range names {
+		agents[name] = getCommand
+	}
+}
+
+func coreAgentMain() *cobra.Command {
+	return command.MakeCommand(subcommands.AgentSubcommands())
+}
+
+func init() {
+	registerAgent([]string{"agent", "datadog-agent", "dd-agent"}, coreAgentMain)
+}
+
 func main() {
-	os.Exit(runcmd.Run(command.MakeCommand(subcommands.AgentSubcommands())))
+	process := strings.TrimSpace(os.Getenv("DD_BUNDLED_AGENT"))
+
+	if process == "" {
+		if len(os.Args) > 0 {
+			process = strings.TrimSpace(path.Base(os.Args[0]))
+		}
+
+		if process == "" {
+			executable, err := os.Executable()
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "Failed to determine the Agent process name: %s\n", err.Error())
+				os.Exit(1)
+			}
+			process = executable
+		}
+
+		process = strings.TrimSuffix(process, path.Ext(process))
+	}
+
+	agentCmdBuilder := agents[process]
+	if agentCmdBuilder == nil {
+		fmt.Fprintf(os.Stderr, "Invoked as '%s', acting as main Agent.\n", process)
+		agentCmdBuilder = coreAgentMain
+	}
+
+	rootCmd := agentCmdBuilder()
+	if err := setProcessName(process); err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to set process name as '%s': %s\n", process, err)
+	}
+	os.Exit(runcmd.Run(rootCmd))
 }

cmd/agent/main_common.go

@@ -0,0 +1,13 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-present Datadog, Inc.
+
+//go:build !linux
+
+package main
+
+// nolint: deadcode, unused
+func setProcessName(_ string) error {
+	return nil
+}

cmd/agent/main_linux_cgo.go

@@ -0,0 +1,42 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-present Datadog, Inc.
+
+//go:build linux && cgo
+
+package main
+
+/*
+#include <errno.h>
+#include <sys/prctl.h>
+#include <stdlib.h>
+
+int prctl_err = 0;
+
+int set_process_name () __attribute__((constructor));
+
+int set_process_name()
+{
+	const char *name = getenv("DD_BUNDLED_AGENT");
+	if (name != NULL) {
+		int ret = prctl(PR_SET_NAME, name, 0, 0);
+		if (!ret) {
+			prctl_err = errno;
+		}
+		return ret;
+	}
+	return 0;
+}
+*/
+import (
+	"C"
+)
+import "syscall"
+
+func setProcessName(_ string) error {
+	if C.prctl_err == 0 {
+		return nil
+	}
+	return syscall.Errno(C.prctl_err)
+}

cmd/agent/main_linux_no_cgo.go

@@ -0,0 +1,22 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-present Datadog, Inc.
+
+//go:build linux && !cgo
+
+package main
+
+import (
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+func setProcessName(process string) error {
+	processName := make([]byte, len(process)+1)
+	copy(processName, process)
+	_, _, err := syscall.AllThreadsSyscall(unix.SYS_PRCTL, unix.PR_SET_NAME, uintptr(unsafe.Pointer(&processName[0])), 0)
+	return err
+}

cmd/agent/process_agent.go

@@ -0,0 +1,26 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-present Datadog, Inc.
+
+//go:build !windows && bundle_process_agent
+
+// Main package for the agent binary
+package main
+
+import (
+	"os"
+
+	processcommand "github.com/DataDog/datadog-agent/cmd/process-agent/command"
+	processsubcommands "github.com/DataDog/datadog-agent/cmd/process-agent/subcommands"
+	"github.com/DataDog/datadog-agent/pkg/util/flavor"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	registerAgent([]string{"process-agent"}, func() *cobra.Command {
+		flavor.SetFlavor(flavor.ProcessAgent)
+		os.Args = processcommand.FixDeprecatedFlags(os.Args, os.Stdout)
+		return processcommand.MakeCommand(processsubcommands.ProcessAgentSubcommands(), processcommand.UseWinParams, processcommand.RootCmdRun)
+	})
+}

cmd/agent/security_agent.go

@@ -0,0 +1,23 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-present Datadog, Inc.
+
+//go:build !windows && bundle_security_agent
+
+// Main package for the agent binary
+package main
+
+import (
+	seccommand "github.com/DataDog/datadog-agent/cmd/security-agent/command"
+	secsubcommands "github.com/DataDog/datadog-agent/cmd/security-agent/subcommands"
+	"github.com/DataDog/datadog-agent/pkg/util/flavor"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	registerAgent([]string{"security-agent"}, func() *cobra.Command {
+		flavor.SetFlavor(flavor.SecurityAgent)
+		return seccommand.MakeCommand(secsubcommands.SecurityAgentSubcommands())
+	})
+}

cmd/agent/system_probe.go

@@ -0,0 +1,23 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-present Datadog, Inc.
+
+//go:build !windows && bundle_system_probe
+
+// Main package for the agent binary
+package main
+
+import (
+	sysprobecommand "github.com/DataDog/datadog-agent/cmd/system-probe/command"
+	sysprobesubcommands "github.com/DataDog/datadog-agent/cmd/system-probe/subcommands"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	registerAgent([]string{"system-probe"}, func() *cobra.Command {
+		rootCmd := sysprobecommand.MakeCommand(sysprobesubcommands.SysprobeSubcommands())
+		sysprobecommand.SetDefaultCommandIfNonePresent(rootCmd)
+		return rootCmd
+	})
+}

cmd/agent/trace_agent.go

@@ -0,0 +1,23 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-present Datadog, Inc.
+
+//go:build !windows && bundle_trace_agent
+
+// Main package for the agent binary
+package main
+
+import (
+	"os"
+
+	tracecommand "github.com/DataDog/datadog-agent/cmd/trace-agent/command"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	registerAgent([]string{"trace-agent"}, func() *cobra.Command {
+		os.Args = tracecommand.FixDeprecatedFlags(os.Args, os.Stdout)
+		return tracecommand.MakeRootCommand()
+	})
+}

docs/dev/agent_build.md

@@ -52,6 +52,30 @@ Also note that the trace agent needs to be built and run separately. For more in
 We use `pkg-config` to make compilers and linkers aware of Python. The required .pc files are
 provided automatically when building python through omnibus.
 
+As an option, the Agent can combine multiple functionalities into a single binary to reduce
+the space used on disk. The `DD_BUNDLED_AGENT` environment variable is used to select
+which functionality to enable. For instance, if set to `process-agent`, it will act as the process Agent.
+If the environment variable is not defined, the process name is used as a fallback.
+As the last resort meaning, the executable will behave as the 'main' Agent.
+
+Different combinations can be obtained through the usage of build tags. As an example,
+building the Agent with the `bundle_process_agent` and `bundle_security_agent` will produce
+a binary that has the process Agent and security Agent capabilities.
+
+The `--bundle` argument can be used to override the default set of functionalities bundled
+into the Agent binary. For instance, to override the defaults and bundle only the process and
+and the security Agents:
+
+```
+deva agent.build --bundle process-agent --bundle security-agent
+```
+
+To disable bundling entirely:
+
+```
+deva agent.build --bundle agent
+```
+
 ## Testing Agent changes in containerized environments
 
 Building an Agent Docker image from scratch through an embedded build is a slow process.

omnibus/config/software/datadog-agent.rb

@@ -31,6 +31,11 @@
 build do
   license :project_license
 
+  bundled_agents = []
+  if heroku_target?
+    bundled_agents = ["process-agent"]
+  end
+
   # set GOPATH on the omnibus source dir for this software
   gopath = Pathname.new(project_dir) + '../../../..'
   msgoroot = "/usr/local/msgo"
@@ -83,15 +88,16 @@
     command "inv -e rtloader.clean"
     command "inv -e rtloader.make --install-prefix \"#{install_dir}/embedded\" --cmake-options '-DCMAKE_CXX_FLAGS:=\"-D_GLIBCXX_USE_CXX11_ABI=0\" -DCMAKE_INSTALL_LIBDIR=lib -DCMAKE_FIND_FRAMEWORK:STRING=NEVER -DPython3_EXECUTABLE=#{install_dir}/embedded/bin/python3'", :env => env
     command "inv -e rtloader.install"
+    bundle_arg = bundled_agents ? bundled_agents.map { |k| "--bundle #{k}" }.join(" ") : "--bundle agent"
 
     include_sds = ""
     if linux_target?
         include_sds = "--include-sds" # we only support SDS on Linux targets for now
     end
-    command "inv -e agent.build --exclude-rtloader #{include_sds} --major-version #{major_version_arg} --rebuild --no-development --install-path=#{install_dir} --embedded-path=#{install_dir}/embedded --flavor #{flavor_arg}", env: env
+    command "inv -e agent.build --exclude-rtloader #{include_sds} --major-version #{major_version_arg} --no-development --install-path=#{install_dir} --embedded-path=#{install_dir}/embedded --flavor #{flavor_arg} #{bundle_arg}", env: env
 
     if heroku_target?
-      command "inv -e agent.build --exclude-rtloader --major-version #{major_version_arg} --rebuild --no-development --install-path=#{install_dir} --embedded-path=#{install_dir}/embedded --flavor #{flavor_arg} --agent-bin=bin/agent/core-agent", env: env
+      command "inv -e agent.build --exclude-rtloader --major-version #{major_version_arg} --no-development --install-path=#{install_dir} --embedded-path=#{install_dir}/embedded --flavor #{flavor_arg} --agent-bin=bin/agent/core-agent --bundle agent", env: env
     end
   end
 
@@ -120,8 +126,10 @@
     mkdir Omnibus::Config.package_dir() unless Dir.exists?(Omnibus::Config.package_dir())
   end
 
-  platform = windows_arch_i386? ? "x86" : "x64"
-  command "invoke trace-agent.build --install-path=#{install_dir} --major-version #{major_version_arg} --flavor #{flavor_arg}", :env => env
+  if not bundled_agents.include? "trace-agent"
+    platform = windows_arch_i386? ? "x86" : "x64"
+    command "invoke trace-agent.build --install-path=#{install_dir} --major-version #{major_version_arg} --flavor #{flavor_arg}", :env => env
+  end
 
   if windows_target?
     copy 'bin/trace-agent/trace-agent.exe', "#{install_dir}/bin/agent"
@@ -130,7 +138,9 @@
   end
 
   # Process agent
-  command "invoke -e process-agent.build --install-path=#{install_dir} --major-version #{major_version_arg} --flavor #{flavor_arg}", :env => env
+  if not bundled_agents.include? "process-agent"
+    command "invoke -e process-agent.build --install-path=#{install_dir} --major-version #{major_version_arg} --flavor #{flavor_arg}", :env => env
+  end
 
   if windows_target?
     copy 'bin/process-agent/process-agent.exe', "#{install_dir}/bin/agent"
@@ -180,7 +190,7 @@
     copy 'bin/cws-instrumentation/cws-instrumentation', "#{install_dir}/embedded/bin"
   end
 
-  # OTel agent
+  # OTel agent - can never be bundled
   if ot_target?
     unless windows_target?
       command "invoke -e otel-agent.build", :env => env